Catalyst for residua demetalation and desulfurization

ABSTRACT

A demetalation and desulfurization catalyst for metal and sulfur containing petroleum oils, e.g., residua containing hydrocarbon components, comprising a hydrogenating component composited on a refractory base, e.g., alumina, having a substantially higher pore volume and more pore volume distributed within the 0-100Å diameter range than such previously known catalysts and method of using same; said catalyst possesses superior aging characteristics.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a division of application Ser. No. 404,786 filed Aug. 3, 1982,which is a continuation of application Ser. No. 42,659, filed May 25,1979, now abandoned, which was a continuation-in-part of Ser. No.714,145, filed Aug. 13, 1976, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is concerned with an improved catalyst and improvedcatalytic process for the demetalation and desulfurization of petroleumoils, preferably those residual fractions with undesirably high metalsand/or sulfur contents. More particularly, the invention utilizes ademetalation-desulfurization catalyst characterized by a novel porevolume and pore size distribution. Additionally, this invention involvescatalysts comprising a Group VIB metal and a Group VIII metal compositedwith an alumina support characterized by a content of gamma phasealumina and a specific pore size distribution.

2. Description of the Prior Art

Residual petroleum oil fractions produced by atmospheric or vacuumdistillation of crude petroleum are characterized by relatively highmetals and sulfur content. This comes about because practically all ofthe metals present in the original crude remain in the residualfraction, and a disproportionate amount of sulfur in the original crudeoil also remains in that fraction. Principal metal contaminants arenickel and vanadium. Iron and small amounts of copper are also sometimespresent. Additionally, trace amounts of zinc and sodium are found insome feedstocks. The high metals content of the residual fractionsgenerally preclude their effective use as charge stocks for subsequentcatalytic processing such as catalytic cracking and hydrocracking. Thisis so because the metal contaminants deposit on the special catalystsfor these processes and cause the premature aging of the catalyst and/orformation of inordinate amounts of coke, dry gas and hydrogen.

It is a current practice to upgrade certain residual fractions by apyrolitic operation known as coking. In this operation the residuum isdestructively distilled to produce distillates of low metals content andleave behind a solid coke fraction that contains most of the metals.Coking is typically carried out in a reactor or drum operated at about800° to 1100° F. temperature and a pressure of one to ten atmospheres.The economic value of the coke by-product is determined by its quality,especially its sulfur and metals content. Excessively high levels ofthese contaminants makes the coke useful only as low-valued fuel. Incontrast, cokes of low metals content, for example up to about 100 ppm(parts-per-million by weight) of nickel and vanadium, and containingless than about 2 weight percent sulfur may be used in high valuedmetallurgical, electrical, and mechanical applications.

Certain residual fractions are currently subjected to visbreaking, whichis a heat treatment of milder conditions than used in coking, in orderto reduce their viscosity and make them more suitable as fuels. Again,excessive sulfur content sometimes limits the value of the product.

Residual fractions are sometimes used directly as fuels. For this use, ahigh sulfur content in many cases is unacceptable for ecologicalreasons.

At present, catalytic cracking is generally done utilizing hydrocarbonchargestocks lighter than residual fractions which generally have an APIgravity less than 20. Typical cracking chargestocks are coker and/orcrude unit gas oils, vacuum tower overhead, etc., the feedstock havingan API gravity from about 15 to about 45. Since these crackingchargestocks are distillates, they do not contain significantproportions of the large molecules in which the metals are concentrated.Such cracking is commonly carried out in a reactor operated at atemperature of about 800° to 1500° F., a pressure of about 1 to 5atmospheres, and a space velocity of about 1 to 1000 WHSV.

The amount of metals present in a given hydrocarbon stream is oftenexpressed as a chargestock's "metals factor." This factor is equal tothe sum of the metals concentrations, in parts per million of iron andvanadium plus ten times the concentration of nickel and copper in partsper million, and is expressed in equation form as follows:

    F.sub.m =Fe+V+10(Ni+Cu)

Conventionally, a chargestock having a metals factor of 2.5 or less isconsidered particularly suitable for catalytic cracking. Nonetheless,streams with a metals factor of 2.5 to 25 or even 2.5 to 50, may be usedto blend with or as all of the feedstock to a catalytic cracker usingfor instance the newer fluid cracking techniques.

In any case, the residual fractions of typical crudes will requiretreatment to reduce the metals factor. As an example, a typical Kuwaitcrude, considered of average metals content, has a metals factor ofabout 75 to about 100. As almost all of the metals are combined with theresidual fraction of a crude stock, it is clear that at least about 80%of the metals and preferably about 90% need to be removed to producefractions (having a metals factor of about 2.5 to 50) suitable forcracking chargestocks.

Metals and sulfur contaminants would present similar problems withregard to hydrocracking operations which are typically carried out onchargestocks even lighter than those charged to a cracking unit. Typicalhydrocracking reactor conditions consist of a temperature of 400° to1,000° F. and a pressure of 100 to 3,500 psig.

It is evident that there is considerable need for an efficient method toreduce the metals and/or sulfur content of petroleum oils, andparticularly of residual fractions of these oils. While the technologyto accomplish this for distillate fractions has been advancedconsiderably, attempts to apply this technology to residual fractionsgenerally fail due to a very rapid deactivation of the catalyst,presumably by metal contaminants. Therefore, it is also evident there isconsiderable need for a demetalation/desulfurization catalyst possessingimproved aging characteristics.

U.S. Pat. No. 3,770,617 describes a hydrodesulfurization process thatemploys a catalyst having an oxide or sulfide of a Group VIB and/orGroup VIII metal on an alumina support characterized by a specific poresize range; U.S. Pat. No. 3,931,052 describes the demetalation anddesulfurization of metal and sulfur containing residual petroleum oilsthrough the use of a catalyst comprising a hydrogenating componentcomposited on an alumina base, whose pores are substantially distributedover a narrow 180 to 300 A diameter range and U.S. Pat. No. 3,383,301(Beuther et al.) which also deals with demetalation and desulfurizationwherein an alumina base catalyst on which is composited a hydrogenatingcomponent is utilized.

U.S. Pat. No. 3,876,523 describes a demetalation/desulfurizationcatalyst capable of reducing the metals content (Ni+V) by as much as 88%and removing over 95% of the sulfur contaminants. However theperformance of this catalyst upon aging leaves something to be desired.

It has now been discovered in accordance with the present invention,that a catalyst which has its pore volume substantially concentrated incertain narrowly defined pore sizes provides a catalyst of overallsuperior demetalation and desulfurization properties, i.e., such acatalyst provides high demetalation and desulfurization when fresh andwhen aged.

Some prior art catalysts such as described in U.S. Pat. Nos. 4,048,060and 4,113,636 possess some properties similar to those of the instantcatalyst but are devoid of others necessary for superior demetalationand desulfurization activity when fresh and after prolonged use.Especially significant are differences in the pore volume attributed topores having diameters ranging from 0 to 100 Å.

SUMMARY OF THE INVENTION

It has now been found that hydrocarbon oils containing both metals andsulfur contaminants may be very effectively demetalized and desulfurizedby contact, in the presence of hydrogen under hydrotreating conditions,with a catalyst comprising a hydrogenation component, e.g., molybdenumoxide or sulfide and cobalt oxide or sulfide, on a refractory base,e.g., a substantially non-acidic alumina support comprising a gammaphase alumina. The catalyst is further characterized by a particularpore volume and pore size distribution. In particular, the catalyst hasat least 50% of its pore volume in pores of 0 to about 100 Å indiameter, with at least 70% of the volume of the pores with a diameterwithin the range of about 0-150 Å and with at least 90% of its porevolume in pores of 0 to about 200 Å in diameter, with no more than about10% of its pore volume in pores of greater than 200 Å in diameter and asurface area of at least about 200 m² /g. and having an average totalpore volume of approximately 0.80 cc/grams. Additionally, in a preferredvariant, at least 25% of the pore volume is in pores of 0 to about 30 Ådiameter, and at least 20% of the pore volume is in pores of about 50 toabout 100 Å diameter. The catalysts in accordance with this inventionprovide, under the reaction conditions hereinafter described, highefficiency for both demetalation and desulfurization with unusually slowaging and high catalyst stability.

The catalysts of this invention are prepared by a sequence ofprocedures, fully described hereinafter, that result in the depositionof hydrogenating material on a gamma phase alumina.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a set of activity curves comparing the demetalation activityof a catalyst according to the present invention, a commercial prototypecatalyst and a commercially available catalyst which are both outsidethe scope of this invention.

FIG. 2 is a set of activity curves comparing desulfurization activityfor a catalyst of the present invention as compared with the abovereferred to commercial prototype and commercially available catalysts.

FIG. 3 shows demetalation and desulfurization activity curves as afunction of temperature for fresh samples of the above referred tocommercial prototype and commercially available catalysts.

FIG. 4 shows demetalation and desulfurization as a function oftemperature for aged samples of the catalysts of FIG. 3.

FIG. 5 shows demetalation and desulfurization activity curves as afunction of temperature for an aged catalyst according to the presentinvention and an aged catalyst referred to above as being a commercialprototype.

FIG. 6 shows demetalation and desulfurization activity curves for unagedcatalysts of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

The catalysts of the invention are prepared by impregnatinghydrogenating components, of Group VIB and Group VIII metals, on asuitable particulate refractory base (in a preferred embodiment, cobaltoxide and molybdenum oxide on a gamma phase alumina); said compositecatalyst having not less than 90% of its pore volume in pores having adiameter within the range of from about 0-200 Å, not less than 25% ofits pore volume in pores having a diameter within the range of fromabout 0-30 Å, not less than 50% of its pore volume in pores having adiameter within the range of from about 0-100 Å, and not more than about10% of its pore volume in pores having a diameter greater than about 200Å; said catalyst further having a surface area of about 180 to 220 m²/gram, a pore volume between about 0.70 and 0.90 cc/gram and an averagepore diameter of about 145 to 170 Å. Catalysts having a surface area ofabout 204 m² /gram, a pore volume of 0.70-0.90 cc/gram, preferably about0.80 cc/gram and an average pore diameter of 157 Å have provenespecially advantageous. In an especially preferred embodiment thecatalyst is further defined as having a hydrogenating componentconsisting essentially of about 2 to about 10 weight percent, preferablyfrom about 3 to 4 weight percent cobalt oxide or sulfide, and about 5 toabout 20 weight percent, preferably from about 9.5 to 11.5 weightpercent molybdenum oxide or sulfide.

Not wishing to be bound by specific theories, it is nevertheless feltthat the uniqueness of this invention's catalysts is at least partiallydue to the fact that the alumina catalyst base is calcined at specifictemperatures thereby producing a specific alumina phase (gamma) having apore size distribution distinct from other aluminas.

The gamma phase is normally reached by starting with an alpha phasemonohydrate. An alpha phase monohydrate enters the gamma phase at about500° C., crosses the transition point into the delta phase at about 860°C. and enters the narrowly temperature banded theta phase at about 1060°C. The transition point between theta and alpha phases is about 1150° C.It should be noted, however, that both beta trihydrate and alphatrihydrate aluminas may also be transformed into the alpha monohydrateform. Thus, the initial alumina need not be an alpha monohydrate.

A metal and/or sulfur containing hydrocarbon chargestock is contactedwith a catalyst of the class of this invention under a hydrogen pressureof about 500 to 3,000 psig and a hydrogen circulation rate of about1,000 to 15,000 scf/bbl of feed, and at about 600° F. to 850° F.temperature and 0.1 to 5.0 LHSV. When higher desulfurization is desiredthe preferred operating conditions are more severe: 725° to 850° F., ahydrogen pressure of 2,000 to 3,000, and a space velocity of 0.10 to 1.5LHSV.

As illustrated in FIGS. 1 and 2, a catalyst according to this inventionhas the ability to dramatically reduce metals content by about 90% andconcomitantly remove more than 80% of the sulfur contaminants whilemaintaining a high degree of catalyst stability. For example, a catalystin accordance with this invention, (Example 2) although less active thanthe commercial prototype, (Example 3) lost very little activity(approximately 1.3% for metals removed and approximately 12.9% forsulfur removal) and was much the more active catalyst at the end of 35days of aging.

The feedstock to be demetalized can be any metal-contaminant containingpetroleum stock, but preferably one containing residual fractions. Aprocess in accordance with the previously described operating conditionsis especially advantageous in connection with chargestocks having ametal factor of greater than about 25.

FIG. 3 is a direct comparison under identical conditions of acommercially available catalyst (Example 1), said commercial prototype acatalyst in accordance with U.S. Pat. Nos. 3,876,523 and 4,082,695 (seeTable 1 "523" patent and below for the properties of said catalyst)identified hereinafter as Example 3 or catalyst 523.

The results in FIG. 3 show said 523 catalyst is capable of reducingmetals content (NI+V) by as much as 98% and removing over 95% of thesulfur contaminants. In comparison, the commercial catalyst (Example 1)would require much higher temperatures to reduce the metals and sulfurlevels to the same extent as Example 3 (catalyst 523). Obviously,catalyst 523 is superior for simultaneous demetalation anddesulfurization of residua than the commercial catalyst (Example 1).

The operating conditions for the above examples comprised 2000 psighydrogen pressure, 0.75 LHSV and 5000 SCF H₂ /bbl of Kuwait atmosphericresiduum having 3.54% by weight sulfur, 12 ppm nickel and 42 ppmvanadium.

However, as revealed in aging tests the performance of catalyst 523leaves something to be desired. Batches of the commercial catalyst and523 were aged simultaneously at 2000 psig, 0.6 LHSV, 5000 SCF H₂ /bblfor 95 days with a 50/50 blend of Kuwait/Lagomedio atmospheric residuahaving 2.85% by weight sulfur, 16 ppm nickel and 110 ppm vanadium. Thetemperature was 725° F. initially and was gradually raised to 775° F. tomaintain about 75% demetalation and desulfurization.

The aged catalysts were then retested with Kuwait atmospheric residuumhaving 4.01% by weight sulfur, 11 ppm nickel and 50 ppm vanadium at thesame conditions as the unaged catalyst tests. FIG. 4 shows thedemetalation and desulfurization activity curves as a function oftemperature for both aged catalysts. It shows the superior agingcharacteristics of catalyst 523 for demetalation. Although the aged 523still shows substantial desulfurization activity, it is clear that it isless active for desulfurization than the aged commercial catalyst. Forexample, at 775° F., desulfurization is 61% for catalyst 523 and 76% forExample 1. Thus, it is evident that better retention of desulfurizationactivity would be a desirable characteristic of ademetalation-desulfurization catalyst.

The concept catalyst of this invention has those characteristics. Thisis illustrated by the following aging tests. Batches of catalyst 523 anda catalyst in accordance herewith (Example 2) were aged simultaneouslyat 2000 psig, 0.6 LHSV, 4000 SCF H₂ /bbl for 35 days with Lagomedioatmospheric residuum containing 2.02% by weight sulfur, 18 ppm nickeland 180 ppm vanadium. The temperature was raised from an initial 725° F.to about 765° F. at end of run to maintain about 75% demetalation and60-70% desulfurization.

The aged catalysts were then tested with Kuwait atmospheric residuumhaving 4.01 by weight sulfur, 11 ppm nickel and 50 ppm vanadium at thesame conditions as the earlier activity tests. FIG. 5 shows demetalationand desulfurization activity curves as a function of temperature for theaged catalysts. It shows that a catalyst of this invention is equal tocatalyst 523 (Example 3) in demetalation activity and superior to it indesulfurization activity. In fact, examination of the desulfurizationresults in FIGS. 4 and 5 would indicate that the aged catalyst of thisinvention has the same superiority in desulfurization activity to the523 catalyst that the aged commercial catalyst does. Thus, the instantcatalysts have the same excellent aging characteristics for demetalationthat the 523 catalyst has and the desulfurization characteristics thatthe commercial catalyst (Example 1) has.

Actually, the aging characteristics of our catalysts are considerablybetter than those of 523. They lose less demetalation and lessdesulfurization activity than is indicated by FIG. 5, because ourcatalysts are slightly less active in the unaged state. This is shown inthe results of FIG. 6, for unaged 523 and an unaged catalyst of thisinvention (Example 2), for hydrotreating the Kuwait atmospheric residuumdescribed above.

From what has been said, it will be clear that the feedstock can be awhole crude. However, since the high metal and sulfur content of a crudeoil tend to be concentrated in the higher boiling fractions, the presentprocess more commonly will be applied to a bottoms fraction of apetroleum oil, i.e., one which is obtained by atmospheric distillationof a crude petroleum oil to remove lower boiling materials such asnaphtha and furnace oil, or by vacuum distillation of an atmosphericresidue to remove gas oil. Typical residues to which the presentinvention is applicable will normally be substantially composed ofresidual hydrocarbons boiling above 900° F. and containing a substantialquantity of asphaltic materials. Thus, a suitable chargestock can be onehaving an initial or 5 percent boiling point somewhat below 900° F.,provided that a substantial proportion, for example, about 40 or 50percent by volume, of its hydrocarbon components boil above 900° F. Ahydrocarbon stock having a 50 percent boiling point of about 900° F. andwhich contains asphaltic materials, 4% by weight sulfur and 51 ppmnickel and vanadium is illustrative of such chargestock.

The hydrogen gas which is used during thehydrodemetalation-hydrodesulfurization is circulated at a rate betweenabout 1,000 and 15,000 scf/bbl of feed and preferably between about3,000 and 8,000 scf/bbl. The hydrogen purity may vary from about 60 to100 percent. If the hydrogen is recycled, which is customary, it isdesirable to provide for bleeding off a portion of the recycle gas andto add makeup hydrogen in order to maintain the hydrogen purity withinthe range specified. Satisfactory removal of hydrogen sulfide from therecycled gas will ordinarily be accomplished by such bleed-offprocedures. However, if desired, the recycled gas can be washed with asolvent for hydrogen sulfide or otherwise treated in known manner toreduce the hydrogen sulfide content thereof prior to recycling.

The invention is especially beneficial where thehydrodemetalation-desulfurization is effected without concomitantcracking of the hydrocarbons present in the feedstock. To achieve thisresult, the temperature and space velocity are selected within theranges specified earlier that will result in the reduction of the metalscontent of the feedstock of about 75 to 98%, preferably over 90%.

The hydrogenating component of the class of catalysts disclosed hereincan be any material or combination thereof that is effective tohydrogenate and desulfurize the chargestock under the reactionconditions utilized. For example, the hydrogenating component can be acombination of Group VIB and Group VIII metals in a form capable ofpromoting hydrogenation reactions, especially effective catalysts forthe purposes of this invention are those comprising molybdenum oxide andat least one member of the iron group metals. Preferred catalysts ofthis class are those containing cobalt oxide and molybdenum oxide, butother combinations of iron group metals and molybdenum including iron ornickel, as well as combinations of nickel and tungsten or other GroupVIB and Group VIII metals of the Periodic Table taken in combination.The hydrogenating components of the catalysts of this invention can beemployed in sulfide or oxide form.

When the use of a catalyst in sulfide form is desired, the catalyst canbe presulfided, after calcination, or calcination and reduction, priorto contact with the chargestock or by contact with a sulfiding mixtureof hydrogen and hydrogen sulfide, at a temperature in the range of about400° to 800° F., at atmospheric or elevated pressures. Presulfiding canbe conveniently effected at the beginning of an onstream period at thesame conditions to be employed at the start of such period. The exactproportions of hydrogen and hydrogen sulfide are not critical, andmixtures containing low or high proportions of hydrogen sulfide can beused. Relatively low proportions are preferred for economic reasons.When the unused hydrogen and hydrogen sulfide utilized in thepresulfiding operation is recycled through the catalyst bed, any waterformed during said presulfiding is preferably removed prior torecycling. It will be understood that elemental sulfur or sulfurcompounds, e.g., mercaptans, or carbon disulfide that are capable ofyielding hydrogen sulfide at the sulfiding conditions, can be used inlieu of hydrogen sulfide.

Although presulfiding of the catalyst is preferred, it is emphasizedthat this is not essential as the catalyst will normally become sulfidedin a very short time by contact, at the process conditions disclosedherein, with the high sulfur content feedstocks to be used.

For purposes of this invention, it is preferred to operate with catalystparticles such as 1/32" extrudate (1/16" may also be used ascircumstances may require) or the equivalent disposed in one or morefixed beds. Furthermore, the catalyst described herein may beeffectively used in a dual catalytic system or as the sole catalyst inthe process of this invention.

The following examples serve to illustrate the catalyst and process ofthe invention without limiting same.

In these specific embodiments, Example 1 is a typical commerciallyavailable catalyst containing about 3.4% wt. CoO and about 13.4% wt.MoO₃ hereinafter described in greater detail. Example 2 isrepresentative of the catalysts of the invention and Example 3 is acommercial prototype catalyst having a different pore volumedistribution fully described in U.S. Pat. No. 3,876,533 as SMO 8066.Examples 2 and 3 were prepared by cobalt-molybdenum oxide deposition onalumina as further described below.

EXAMPLE 1

The commercial catalyst identified herein as Example 1 has the followinggeneral properties:

    ______________________________________                                        Packed density     0.79    g/cc                                               Surface area       286     m.sup.2 g                                          Pore volume        0.491   cc/g                                               Particle density   1.28    g/cc                                               Real density       3.42    g/cc                                               Pore diameter      69 Angstrom units                                          CoO                3.4% wt.                                                   MoO.sub.3          13.4% wt.                                                  SiO.sub.2          4.91% wt.                                                  Ni                 0.18% wt.                                                  ______________________________________                                    

EXAMPLE 2

A preparation procedure for the demetalation-desulfurization catalystsof this invention may be exemplified as follows: 212 grams of an aluminabase catalyst (gamma phase) having properties as detailed below, wereimpregnated with a 168 ml solution containing 30.0 grams of ammoniumheptamolybdate (81.9% MoO₃).

    ______________________________________                                        Starting material - 1/32" diameter extrudate                                  ______________________________________                                        Packed density  =     0.42   g/cc                                             Solution capacity                                                                             =     0.8    cc/g                                             Surface area    =     209    in.sup.2 /g                                      Pore volume     =     0.966  cc/g                                             Particle density                                                                              =     0.81   g/cc                                             Real density    =     3.72   g/cc                                             Pore diameter   =     185 Angstrom units                                      ______________________________________                                    

The impregnated pellets were then dried in an oven at about 250° F. forabout 3 hours, the dried product was thereafter impregnated with a 154ml solution containing 33.3 grams of cobalt nitrate hexahydrate.

The pellets were again dried in an oven at about 250° F. and thencalcined in shallow dishes by heating to 1000° F. at a rate of 5° F./minand holding at about 1000° F. for about 10 hours. Properties of theresulting catalyst were:

    ______________________________________                                               Packed density                                                                          =     0.51   g/cc                                                   Surface area                                                                            =     204    cc.sup.2 /g                                            Pore volume                                                                             =     0.801  cc/g                                                   Particle density                                                                        =     0.94   g/cc                                                   Real density                                                                            =     3.71   g/cc                                                   Pore diameter                                                                           =     157A                                                          CoO         31/2% wt.                                                         MoO.sub.3   10% wt.                                                    ______________________________________                                    

EXAMPLE 3

A preparation procedure for a demetalation-desulfurization catalyst ofthe commercial prototype i.e., catalyst 523 may be exemplified asfollows:

About 525.0 grams of 1/32" extrudate alumina were calcined to atemperature of about 1950° F. thereby transforming the alumina into aparticular alumina at about the transition point between delta and thetaphases. Water was added to approximately 91.7 grams of ammoniummolybdate (about 81.0% MoO₃) until a total volume of about 289.0 ml. wasreached. This ammonium molybdate solution-water solution was mixed withthe alumina which had been placed under a vacuum for about one halfhour, and while still under a vacuum was slightly agitated or rolled forabout 5 minutes. The vacuum was removed from the mixture, and 230° F.heat was applied for about 4 hours producing a weight loss due to thedrying of about 236.9 grams. Water was added to approximately 69.4 gramsof CoCl₂.6H₂ O (about 99.0% purity) until a total volume of about 239.0ml. was reached. This cobalt chloride-water solution was mixed with themolybdenum vacuum impregnated alumina and placed under a vacuum forabout one half hour, and while still under a vacuum, was slightlyagitated for about 5 minutes. The vacuum was removed from the mixture,and 230° F. heat was applied for about ten hours. Finally, thecobalt-molybdenum impregnated alumina was calcined to about 1000° F. ata gradually increasing rate of approximately 2° F./min., and held at1000° F. for about ten hours.

The pore volume distribution of the three catalysts was as follows:

    ______________________________________                                        Catalyst    Example 1  Example 2  Example 3                                   ______________________________________                                        Pore volume, cc/g                                                                         0.491      0.80       0.49                                        % of PV in pores of                                                           0-30A diameter                                                                            7                29           4                                   30-50       28               2            3                                   50-80       61          97   11      52   3       14                          80-100      1                10           4                                   100-150     1                19           30                                  150-200     0                22           35                                  200-300     0                4            12                                  >300        2                3            9                                   Particle size, inches                                                                     1/32           1/32       1/32                                    ______________________________________                                    

The catalysts of Examples 1, 2 and 3 were tested for demetalation anddesulfurization activity. The activity tests used Kuwait atmosphericresidua (about 3.5-3.9 wt. % sulfur, 51-54 ppm Ni+V) at nominally 675°,725°, 775° F., 2000 psig, about 0.75 LHSV; the detailed results forExample 2 catalysts are shown in Table 1 and for Example 3 in Table 2.These detailed results were used to normalize activity to 750° F. and0.75 LHSV. The normalized activity results for the fresh and agedcatalyst are summarized briefly as follows:

    ______________________________________                                        Normalized for 750° F., 0.75 LHSV, 2000 psig                           Catalysts:         Example 2 Example 3                                        ______________________________________                                        Metals (Ni + V) Removal, %                                                    Fresh Catalyst     89.3      96.6                                             Aged Catalyst      88.0      83.5                                                                 1.3      13.1                                             Sulfur Removal, %                                                             Fresh Catalyst     81.7      90.4                                             Aged Catalyst      68.8      44.4                                                                12.9      46.0                                             ______________________________________                                    

which clearly illustrates the high level of activity and the improveddemetalation-desulfurization stability of catalysts of this invention.

The catalysts were aged in Lagomedio residua (described below) and thentested as aged catalysts, in said Kuwait residua. The resultsdemonstrate the improved stability of catalysts in accordance herewith.Venezuelan Lagomedio atmospheric residua was used, having about 2.0-2.5wt. % sulfur, 195-205 ppm Ni+V to age said catalysts. Hydrotreatingconditions were: 2000 psig, 0.5 LHSV, about 3900 SCF/B hydrogencirculation and an average temperature of about 750° F. The catalystswere tested for demetalation and desulfurization activity for a 35 dayperiod. Thereafter the activity was again tested using the Kuwaitresidua.

FIG. 1 shows a comparison of the demetalation aging rates of Examples 2and 3 along with the estimated demetalation aging rate of theaforementioned commercial catalyst (Example 1). FIG. 2 is a similarcomparison of the desulfurization aging rates of these catalysts and theestimated desulfurization aging rate of said commercially availablecatalyst. The estimates are based on extensive experience in using thiscatalyst in the demetalation and desulfurization of residualchargestocks having significant metals and/or sulfur content. FIGS. 1and 2 thus illustrate the improved catalysts in accordance with thisinvention.

FIGS. 3 and 4 represent a comparison of fresh and aged activity ofExample 1 and Example 3; FIGS. 5 and 6 present a comparison of fresh andaged activity of Examples 2 and 3. A comparison of these figures clearlyestablishes the overall excellence of catalysts in accordance with thisinvention and their superior demetalation/desulfurization activity afterprolonged use or aging.

Although the preferred embodiments of the invention have beenillustrated, it is to be understood that the invention is not limitedthereto and may be otherwise variously embodied as one of ordinary skillin the art will readily understand.

                                      TABLE 1                                     __________________________________________________________________________    RESULTS OF USING THE CATALYST OF EXAMPLE 2                                    Catalyst:    Fresh               AFTER 35 DAYS AGING                          __________________________________________________________________________                 Charge*             Charge*                                      Temperature °F.                                                                          675  727  773       676  726 777                            Space Velocity LHSV                                                                             .73  .71  .71       .65  .89 .69                            Hyd. Circ., SCF/B 4773 4041 3940      4971                                    Hyd. Consump., SCF/B                                                                            310  470  612       95   202 103                            Sulfur, % Wt.                                                                              3.56 177  .88  .47  4.01 2.88 2.23                                                                              .98                            % Desulfurization 56.8 78.8 88.8      29.1 45.7                                                                              76.6                           Nickel ppm   12   6.8  3.0  1.5  11   8.7  6.9 1.0                            Vanadium ppm 38   17   7.1  2.1  50   23   14  .9                             % Demetalation    53   80   93        48   66  97                             Mol Wt.           468  470  410  494  473  447 409                            Hydrogen % Wt.                                                                             11.78                                                                              12.02                                                                              12.28                                                                              12.44                                                                              11.45                                                                              11.64                                                                              11.79                                                                             12.21                          API Gravity Measurement                                                                    18.8 21.2 23.6 26.9 16.7 19.3 20.9                                                                              25.4                           Nitrogen % Wt.                                                                             .19  .18  .15  .099 .21  .20  .18 .14                            __________________________________________________________________________     *Kuwait Atmospheric Residua                                              

                                      TABLE 2                                     __________________________________________________________________________    RESULTS OF USING THE CATALYST OF EXAMPLE 3                                    Catalyst:     Fresh                AFTER 35 DAYS AGING                        __________________________________________________________________________                  Charge*             Charge*                                     Temperature °F.                                                                           674  727  776       676  725  775                          Space Velocity LHSV                                                                              .73  .79  .73       .72  .70  .72                          Hyd. Circ., SCF/B  5360 3140 3950      4733 4348 4001                         Hyd. Consump., SCF/B                                                                             380  500  840       104  208  367                          Sulfur, % Wt. 356  1.23 .65  .16  4.01 3.42 2.69 1.62                         % Desulfurization  66.1 82.2 95.6      15.4 34.2 60.9                         Nickel ppm    12   4.5  1.7  .3   11   9.8  5.5  1.9                          Vanadium ppm  38   9.4  2.7  .2   50   28   11   2.2                          % Demetalation     72.1 91.3 99.0      38   73   93                           Mol. Wt.                          494  477  449  264                          Hydrogen % Wt.                                                                              11.78                                                                              12.16                                                                              12.36                                                                              12.86                                                                              11.45                                                                              11.62                                                                              11.78                                                                              12.03                        API° Gravity Measurement                                                             18.8 22.9 25.3 28.7 16.7 19.9 20.9 24.0                         Nitrogen % Wt.                                                                              .19  .16  .13  .07  .21  .20  .19  .16                          __________________________________________________________________________     *Kuwait Atmospheric Residua                                              

What is claimed is:
 1. A hydrometalation-desulfurization catalystcomprising a hydrogenating component which comprises a Group VI-B metaloxide or sulfide and a Group VIII metal oxide or sulfide composited witha porous alumina base, said catalyst having at least about 25% of thevolume of the pores with a diameter within the range of about 0 to 30 Å,at least about 50% of the volume of the pores with a diameter within therange of about 0 to 100 Å and further having a pore volume of from about0.80 to about 0.95 cc/gram and an average pore diameter of about 145 Åto about 170 Å and a surface area of about 180 m² /gram to about 220 m²/gram.
 2. The catalyst as claimed in claim 1 wherein said hydrogenatingcomponent consists essentially of about 2 to about 10 weight percentcobalt oxide and about 5 to about 20 weight percent molybdenum oxide. 3.The catalyst as claimed in claim 1 wherein the hydrogenating componentconsists of sulfides of cobalt and molybdenum.
 4. The catalyst asclaimed in claim 1 wherein said hydrogenating component consistsessentially of about 2 to about 10 weight percent nickel oxide and about5 to about 20 weight percent molybdenum oxide.
 5. The catalyst asclaimed in claim 1 wherein the hydrogenating component consists ofsulfides of nickel and molybdenum.
 6. The catalyst of claim 1 whereinthe pore volume distribution is further defined as follows: at least 70%of the volume of the pores with a diameter within the range of about 0to about 150 Å, at least 90% of the volume of the pores with a diameterwithin the range of about 0 to about 200 Å and no more than about 10% ofthe volume of the pores with a diameter greater than about 200 Å
 7. Thecatalyst as claimed in claim 1 wherein said alumina consists essentiallyof gamma phase alumina.
 8. The catalyst as claimed in claim 2 whereinsaid catalyst is produced by impregnating gamma phase alumina pelletswith appropriate amounts of a suitable molybdenum compound and a cobaltcompound and then calcining the dried pellets at about 1000° F. forabout 3 to about 10 hours.